FIG. 1 is a schematic circuit structure of an organic light emitting diode (OLED) pixel circuit of an organic light emitting diode display panel. As shown, the organic light emitting diode pixel 100 includes transistors 102, 104, 106, 108, 110, 112, capacitors 114, 116 and an organic light emitting diode 118; wherein the transistors 102, 104, 106, 108, 110 and 112 may be implemented by P-type transistors. In addition, as shown in FIG. 1, the configuration of the organic light emitting diode pixel 100 is associated with a supply voltage OVDD, a reference voltage OVSS, a data signal VDATA, a predetermined voltage VINT, scan signals S1, S2 and an enable signal EM. FIG. 2 is a schematic timing sequence diagram of the scan signals S1, S2 and enable signal EM. To drive the organic light emitting diode pixel 100 to display a specific image according to the data signal VDATA, a plurality of series-connected circuit stages, arranged in a shift register circuit (not shown), each are configured to provide a respective group of scan signals S1, S2 and enable signal EM.
In a conventional shift register circuit, each circuit stage may include more than about fifty transistors; accordingly, the conventional shift register circuit may have a complicated circuit design, a large circuit size and a high cost.